The present invention relates in general to a heating apparatus which incorporates a heat source interiorly or exteriorly of a heating chamber and is adapted to char an article to be heated or foodstuff to be cooked to a desired degree. In particular, the invention concerns a heating apparatus which is provided with a controller for performing a proper heating by automatically changing-over heating modes in dependence on the detected charring formed in an article to be heated such as foodstuff to be cooked.
In the field of heating apparatus or cooking apparatus such as electric oven, gas oven (or grill), oven range or the like in which an article to be heated or foodstuff to be cooked as accommodated within a heating chamber is subjected to hot air or infrared energy supplied from an electrical heater or gas burner, there has been a demand for charring the article to be heated or foodstuff to be cooked and controlling the degree of charring and hence the finished state of the processed article or foodstuff in a selectively set heating mode.
In hitherto known household cooking apparatus, the temperature of an article or foodstuff being processed is detected by means of a thermometer or alternatively by a bimetal strip to control an energy supply source when the temperature has attained a predetermined level. However, with the control system of this type, it has been impossible to control the degree of charring or superficial charring appearing at the surface of the article being heated. Consequently, the charring of the article or foodstuff being cooked in the conventional heating or cooking apparatus is visually observed to control the energy supply source or alternatively controlled by setting a heating time duration with the aid of a timer on the basis of prior experiences. It goes without saying that great difficulty is encountered in obtaining desired degrees of charring on various articles or foodstuff merely in dependence on the so-called sixth sense or experience.Obviously, the heating time duration for attaining a desired degree of charring will vary widely in dependence on various factors such as mass, water content, composition, shape and the like of the article or foodstuff. Thus, considerable skill is required for setting a proper heating duration for charring an article to a satisfactory degree. In reality, excessive heating or insufficient heating is frequently involved due to improper setting of the heating duration. Such being the circumstance, the user has to observe constantly the charred state of an article concerned, even when a timer for controlling the heating duration on the basis of experimentally obtained data is provided for the cooking apparatus. Thus, the user of the hitherto known heating or cooking apparatus is burdened with great inconvenience.